1. Field of the Invention
This invention relates to a process and apparatus for simultaneously drying and heat treating never-dried wet spun aramid fibers over tensioning rolls in a single step on a continuous basis.
2. Description of the Prior Art
U.S. Pat. No. 3,503,231 issued Mar. 31, 1970 on the application of Fleissner et al., discloses a continuous conveyer belt system for treating materials, including heat treating yarns. The conveyer must be steam pervious and the treatment does not include drying never-dried, wet spun, yarns.
U.S. Pat. No. 3,869,430 issued Mar. 4, 1975 on the application of Blades, discloses, in a general way, drying and heat treating an unsupported, wet, yarn of poly(p-phenylene terephthalamide).
U.S. Pat. Nos. 4,374,978 issued Feb. 22, 1983 and 4,440,710 issued April 3, 1984, on the applications of Fujiwara et al., disclose a process for making fibers of poly(p-phenylene terephthalamide) by washing and drying them in the absence of any tension and then heat treating them under tension at temperatures of greater than 200.degree. C.
U.S. Pat. No. 4,419,317 issued Dec. 6, 1983 on the application of Fujiwara et al., discloses a process for making fibers of poly(p-phenylene terephthalamide) by washing and treating with saturated steam in the absence of tension.
European Patent Application 121,132 published Oct. 10, 1984 on the application of Akihiro et al., discloses the application of finely divided inorganic particles to wet fibers in order to prevent fiber-to-fiber adhesion. The fibers are dried without drawing and are, then, heat treated under tension.
European Patent Application 247,889 published Dec. 2, 1987 on the application of Chern et al., discloses a process for simultaneously drying and heat treating unsupported never-dried para-aramid fibers under high temperatures and high tensions.
Japanese Patent Laid-Open Publication (Kokai) 49-81619 published Aug. 6, 1974 on the application of Nagasawa et al., discloses a fiber treatment wherein never-dried aramid fibers can be dried and heat treated at the same time.